This invention relates to rapid texture prototyping for moulded articles.
Many moulded articles are made with a textured surface finish. Examples include interior trim parts for automobiles, knobs and handles for cooking utensils, garden furniture, casings for audio and video equipment, computers and calculators, and so on. Many of these items are made from large, expensive moulds. The moulds are first made with a smooth moulding cavity which must then be etched to produce the texture. Etching is done by applying a resist and immersing the mould in acid etchant.
Once etched, it will usually be impossible, or at best highly impracticable, to expunge the texture and apply a different texture. It is vital, therefore, for a designer to have some idea of how the product will look, textured. To this end, computer simulations are proposed in which the item can be imaged to a screen using CAD techniques and a texture superimposed. No matter to what state of excellence this type of simulation can be raised, however, it still cannot give the designer a textured component to build into a prototype assembly of, say, an automobile.
The present invention provides for rapid prototyping for textured-surface moulded articles giving authentic pre-appreciation of both appearance and feel.
The invention comprises a method for simulating a mould-imparted texture comprising applying a textured skin to a moulding from a pre-textured mould.
The skin may comprise a skin layer with relief material attached thereto as a texture. The skin layer may constitute a release backing peeled off the moulding after application of the relief material thereto. The relief material may be preferentially adhered to the moulding to enable peel off of the release backing.
However, the skin layer may be soluble and be dissolved after the relief material is adhered to the moulding. The skin layer may be soluble in a paint which is applied after application to the mouldingxe2x80x94the skin layer then becomes absorbed into the paint layer.
The skin may be burnished on to the mouldingxe2x80x94this may be done before and/or after removal of the skin layer; if done before, burnishing serves the purpose of improving adhesion to the moulding and helping to smooth out any imperfections in application. Burnishing may be effected by a densely-bristled brush, though other burnishing tools may be found more appropriate to specific patterns.
As to patterns, the texture may be a random pattern texture, such as the popular leather and woodgrain finishes. A textured skin suitable for such finishes is commercially available glass engraving resist, in which a resist pattern is carried on a release sheet for application to a glass surface which is then sand blasted, the glass surface being eroded except beneath the resist which is then removed. In the present application, the resist material becomes part of the textured surface of the moulding.
The method of the invention is particularly advantageous, however, with geometric patterns used as texture. Such patterns can be readily created by a CAD arrangement which can control a cutting arrangement to cut the pattern into sheet material e.g. vinyl plastics sheeting. Such sheeting may be presented (in different thickness) on a release backing from which cut sheet may be separated, by differential bonding, on to a separate release sheetxe2x80x94there being then xe2x80x98positivexe2x80x99 and xe2x80x98negativexe2x80x99 versions of the pattern. Either release sheet then forms the skin layer of the textured skin.
Whilst the overall effect of a randomxe2x80x94leather, woodgrain etcxe2x80x94pattern may be visualizable by skilled designers, the way a regular geometric pattern texture sits on a curved surface is less easy to imagine. Indeed, difficulties are experienced in engraving even moderately complicated moulds with geometric pattern textures as a resist-carrying backing sheet usually has to be creased to fit the mould. Often, a regular geometric texture simply cannot be applied because of the difficulties of engraving the mould, this explaining a preponderance of random textures, principally leathers.
However, for prototyping purposes as disclosed herein, the skin may be arranged to be stretchable to fit without creasing on to the moulding and the texture is imparted to the skin (as by a CAD arrangement) in distorted fashion to compensate for skin stretching to fit the moulding. Once perfected and approved, Me same technique can then be used to make a stretchy resist for application to the mould from which the moulding was taken. It is possible to take severalxe2x80x94indeed as may as may be required mouldings from the untextured mould for perfection of a pattern and for investigation of the visual and tactile effects of different texture patterns or different orientations of a single pattern.